Many common audio and video codecs support multiple different quality levels and/or resolutions. Each level of quality and/or resolution associated with each codec may comprise a different bandwidth requirement. For example, for a particular codec an endpoint may support two levels of resolution (e.g., 1080p and 720p) and for each resolution it may support three different levels of quality (e.g., good, better, and best). The bandwidth requirements for such an endpoint may be as follows:
1080p at best quality may require 4 Mbps
1080p at better quality may require 3.5 Mbps
1080p at good quality may require 3 Mbps
720p at best quality may require 2.5 Mbps
720p at better quality may require 1.5 Mbps
720p at good quality may require 1 Mbps
One way to take advantage of the varying bandwidths is through the use of layered video coding, Endpoints that support layered video coding (e.g., H.264 scalable video coding (SVC)) may encode the video into a stand alone base layer that contains a base quality version of the stream and then may include multiple additional layers that each provide incremental quality enhancements over the previous layer.